Canonical Comet Apps

by Dylan SchiemannJanuary 24th, 2008

In Michael Carter’s recent post Comet’s Disappointing Mindshare, he argued that Comet has very limited mainstream exposure. But while the average person may not have heard of Comet, there are a significant number of great Comet-based apps on the market today.

Gmail Chat

Shortly after Google launched Google Talk, they added chat to the Gmail interface, providing low-latency IM to all Gmail users. Alex Russell quickly dissected their implementation and learned that Google uses the forever-frame technique. Michael Carter made progress on understanding the htmlfile hack for Internet Explorer.


Thinkature is a collaborative diagramming tool (think Visio or OmniGraffle for the web, with many simultaneous participants). Thinkature uses YUI on the front-end, and what appears to be the long-polling technique with a Twisted-based Comet server.


Meebo is the ultimate web-based chat destination, with access to all of the major IM protocols, as well as chat where you can easily share audio, video, and pictures. Meebo is well known for its use of lighttpd, a very lightweight web server that is often used with Comet techniques.


(Disclosure: I helped build Renkoo through its “beeta” release). Renkoo is an application that strives to solve the problem of getting people together in groups larger than two, but more informally than a planned party. As such, the application includes real-time chat and real-time updates to event information. It uses Dojo on the front-end and repubsub, a mod_pubsub derivative, as its Comet server. repubsub is interesting in that the publish-subscribe paradigm is applied to the server side as well, where information is stored as topics.


A very early Comet company (they originally released mod_pubsub as open source, and the founders of Renkoo were at KnowNow in its early days), KnowNow has emerged with a real-time information portal and aggregation tool for businesses. Think RSS feed reader for all types of data sources. Dojo is used on the front-end, with their own custom Comet server on the back-end.

Lightstreamer and Stock Quotes

(Disclosure: SitePen helped build the Dojo portion of this demo). Lightstreamer, another pioneer in Comet techniques, is known for its usage in the financial industry. Their stock quotes demo shows the power of their easy to use Comet server with Dojo’s dynamic charting engine.


Caplin, yet another early Comet adopter, is also known for their presence in the financial markets. They build their applications on top of a custom Comet implementation. It’s not surprising that so many early Comet engines were driven by the financial services industry’s need for real-time information.

Developing Markets Live

The Financial Times’ Developing Markets Live is “an event-driven blog built on WordPress, where the blog homepage can sit open for a whole day on a trader’s screen and accumulate posts as they are made, plus an hour-long live chat at 11am London time every trading day. This is all powered by Meteor, an open source event-driven webserver designed to distribute real time data to thousands of subscribers efficiently.”

One Response to “Canonical Comet Apps”

  1. Lars Strojny Says: and are definitely missing in this list :-)

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